PROBLEMS: Add the parameter file for the Orszag-Tang problem.

Signed-off-by: Grzegorz Kowal <grzegorz@amuncode.org>

problems/orszag-tang.in

@@ -0,0 +1,46 @@
+# problem name and parameters
+#
+problem               = "Orszag-Tang"
+
+# physics
+#
+equation_system      = "mhd"
+equation_of_state    = "adi"
+glm_source_terms     = "kepes"
+
+# methods
+#
+time_advance         = "ssprk3(2)4"
+riemann_solver       = "kepes"
+reconstruction       = "mp5"
+
+# mesh parameters
+#
+xmin                 = -5.00d-01
+xmax                 =  5.00d-01
+ymin                 = -5.00d-01
+ymax                 =  5.00d-01
+
+# refinement control
+#
+ncells               = 32
+maxlev               = 5
+refinement_variables = "dens pres vort curr"
+
+# boundary conditions
+#
+xlbndry              = "periodic"
+xubndry              = "periodic"
+ylbndry              = "periodic"
+yubndry              = "periodic"
+zlbndry              = "periodic"
+zubndry              = "periodic"
+
+# runtime control parameters
+#
+tmax                 = 5.0d-01
+cfl                  = 5.0d-01
+
+# data output control
+#
+snapshot_interval    = 1.0d-02